Symbiotic stars (SySt) are interacting binaries where a red giant (RG) fuels
a white dwarf (WD) or a neutron star (NS) companion via accretion (either
through Roche-lobe overflow or wind intercept). Systems harboring NSs are a
recent addition to this class of celestial objects
[1]}, [2]}, [3]}, [4]}, [5]}, [6]} and
constitute a few percent of the known total [7]}, the
vast majority containing WDs [8]}, [9]}, [10]}. For some time, a main
sequence star accreting from the RG at very high rates (10\(^{-6}\)  to
10\(^{-4}\)  M\(_\odot \)  yr\(^{-1}\) ) was considered a viable scenario for SySt in
general [11]}, but this has been progressively
abandoned in the light of expanding observational data, especially in the
far UV and X-rays [12]}, [13]}, [14]}, [15]}, [16]}, [17]}. Even if we will focus on RG+WD systems, the results
of this paper are independent on the actual nature of the accreting star.
